package com.bstek.bdf4.utils;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import lombok.experimental.UtilityClass;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.core.MethodParameter;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.core.annotation.SynthesizingMethodParameter;
import org.springframework.web.method.HandlerMethod;

/**
 *  获取注解类信息
 */
@UtilityClass
public class ClassUtils extends org.springframework.util.ClassUtils {
  private final ParameterNameDiscoverer PARAMETERNAMEDISCOVERER = new DefaultParameterNameDiscoverer();

  /**
   * 获取方法参数信息
   * @param constructor 构造器
   * @param parameterIndex 参数序号
   * @return {MethodParameter}
   */
  public MethodParameter getMethodParameter(Constructor<?> constructor, int parameterIndex) {
    MethodParameter methodParameter = new SynthesizingMethodParameter(constructor, parameterIndex);
    methodParameter.initParameterNameDiscovery(PARAMETERNAMEDISCOVERER);
    return methodParameter;
  }

  /**
   * 获取方法参数信息
   * @param method 方法
   * @param parameterIndex 参数序号
   * @return {MethodParameter}
   */
  public MethodParameter getMethodParameter(Method method, int parameterIndex) {
    MethodParameter methodParameter = new SynthesizingMethodParameter(method, parameterIndex);
    methodParameter.initParameterNameDiscovery(PARAMETERNAMEDISCOVERER);
    return methodParameter;
  }

  /**
   * 获取Annotation
   * @param method Method
   * @param annotationType 注解类
   * @param <A> 泛型标记
   * @return {Annotation}
   */
  public <A extends Annotation> A getAnnotation(Method method, Class<A> annotationType) {
    Class<?> targetClass = method.getDeclaringClass();
    // The method may be on an interface, but we need attributes from the target
    // class.
    // If the target class is null, the method will be unchanged.
    Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);
    // If we are dealing with method with generic parameters, find the original
    // method.
    specificMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);
    // 先找方法，再找方法上的类
    A annotation = AnnotatedElementUtils.findMergedAnnotation(specificMethod, annotationType);
    ;
    if (null != annotation) {
      return annotation;
    }
    // 获取类上面的Annotation，可能包含组合注解，故采用spring的工具类
    return AnnotatedElementUtils.findMergedAnnotation(specificMethod.getDeclaringClass(), annotationType);
  }

  /**
   * 获取Annotation
   * @param handlerMethod HandlerMethod
   * @param annotationType 注解类
   * @param <A> 泛型标记
   * @return {Annotation}
   */
  public <A extends Annotation> A getAnnotation(HandlerMethod handlerMethod, Class<A> annotationType) {
    // 先找方法，再找方法上的类
    A annotation = handlerMethod.getMethodAnnotation(annotationType);
    if (null != annotation) {
      return annotation;
    }
    // 获取类上面的Annotation，可能包含组合注解，故采用spring的工具类
    Class<?> beanType = handlerMethod.getBeanType();
    return AnnotatedElementUtils.findMergedAnnotation(beanType, annotationType);
  }

}
